2021/12/03 (Friday)
- Lab in-personnel: Himangshu, Matt
| Status | Beginning Run 75. LN2 transfer three days ago; there's a delay on LHe so we put a little more LN2 in yesterday to keep it at 77K. Throughput and electrical checks two days ago, both OK. Yesterday we blew out the LN2 before retransferring, IVC leak check OK. |
|---|---|
| 1045 | MC(Cernox)/Sorb = 77.4/132.7 K, G2/G1 (fridge+trap1+dump) = 549/602 mbar, 3He pump off. IVC = 0.54 mbar |
| 1100 | Fill LN2 cold trap bath |
| 1110 | Begin blowing out LN2. Main bath (G3) → 576 mbar+1atm |
| 1130 | Main bath pressure falling, looks like blowout is nearly finished. |
| 1135 | MB pressure flat, stop LN2 blowout. |
| 1140 | Remove hose from MB LN2 fill pipe, remove fill pipe from cyostat and put stopper in port, for MB pumpout |
| 1145 | Start pumping out main bath with scroll pump. Takes 9 minutes to fall to 1 mbar. |
| 1200 | Pressurize MB with helium to 177 mbar above 1 atm. |
| 1205 | Isolate MB by closing V1a. Pump out line to the G3 volume with Scroll Pump. Isolate pump, then open 1K Pot speedivalve to check pressure: about 0.027 bar, 55 mbar on P2. Then pump out 1K Pot (needle valve closed) with Scroll Pump to 0.028 mbar on P2. Then close 1K Pot speedivalve and V4a. Open V1a again to monitor bath pressure. |
| 1210 | Let 63 μbar He exchange gas into IVC. |
| 1233 | Start initial LHe transfer |
| Mixture is open to fridge, both sides, and to cold LN2 Trap 1, and to dump. | |
| 1240 | Pressurize 100L transfer Dewar with helium gas, 3.5 PSI |
| 1245 | MC(Cernox)/Sorb = 78.1/137.1 K, IVC = 46 μbar, G1(fridge) = 594 mbar. G3(MB) = 530 mbar+1atm |
| 1300 | MC(Cernox)/Sorb = 67.7/92.4 K, IVC = 19 μbar, G1(fridge) = 520 mbar. G3(MB) = 481 mbar+1atm |
| 1315 | MC(Cernox)/Sorb = 56.3/31.5 K, IVC = 12 μbar, G1(fridge) = 438 mbar. MB = 7.3%. G3(MB) = 466 mbar+1atm |
| 1330 | MC(Cernox)/Sorb = 46.8/7.3 K, IVC = 12 μbar, G1(fridge) = 422 mbar. MB = 30.5%. G3(MB) = 453 mbar+1atm |
| 1345 | MC(Cernox)/Sorb = 36.6/6.9 K, IVC = 8.6 μbar, G1(fridge) = 416 mbar. MB = 56.2%. G3(MB) = 419 mbar+1atm |
| 1400 | MC(Cernox)/Sorb/1K Pot = 35.6/6.3/5.1 K, IVC = 7.4 μbar, G1(fridge) = 451 mbar. MB = 83.9%. G3(MB) = 398 mbar+1atm |
| 1409 | MC(Cernox) = 10.0 K, IVC = 2.2 μbar. Start pumping out IVC with Turbo pump. |
| 1412 | End LHe transfer @ MB 81.6% |
| 1445 | Check Goldman thermometer - seems to be reading out correctly on the new LabVIEW OmniLogger vi. |
| 1455 | MC(Cernox)/Sorb/1K Pot = 4.6/5.6/4.5 K, G1(fridge) = 524 mbar. |
| 1455 | Turbo on IVC = 3.0 nbar |
| 1505 | Tower/Goldman = 4.65/4.53 K. Both are falling. Tower thermometer is falling faster than the Goldman thermometer. |
| 1510 | Tower/Goldman = 4.50/4.50 K. Here they catch up with one another…. |
| 1520 | Tower/Goldman = 4.39/4.48 K. Tower thermometer falling faster than Goldman thermometer, still. |
| 1530 | MC(H35) = 5.40 K. This doesn't seem reliable. MC(Cernox) = 4.39 K. Tower = 4.30 K. So Goldman is pretty close to Cernox. These could all be correct - not sure what parts will cool faster during the initial transfer and while temperatures of different parts are coming into equilibrium. |